Packaging QGC to an .AppImage file for Linux

I am trying to build and package QGC into a standalone .AppImage file for running on Linux (Ubuntu) systems.

My issue is this: I install Qt Creator with desktop gcc for 5.15.2 as described in the QGC developer docs. On Ubuntu 20 with glibc 2.31 I can use Qt Creator to build QGC. Then I try to package it into an .AppImage with LinuxDeployQT. This fails and says I must have glibc <= 2.27.

So I got an installation of Ubuntu 18. This has glibc 2.27 by default. The problem with Ubuntu 18 with glibc is when I install QT Creator with 5.15.2 and try to run QT Creator I get an error saying glibc_2.28 is not found.

If >= 2.28 is required to build with Qt Creator, but <= 2.27 is required to package into an .AppImage how is this usually done? I know there is a way to do it, but I don’t know what it is. The QGC developer docs specify what is needed to build QGC as well as the versioning and deployment strategy, but not how to bundle the app.

Thank you for your help!